Methods useful in the treatment of bone resorption diseases

ABSTRACT

The invention relates to a combined pharmaceutical preparation comprising parathyroid hormone and a bone resorption inhibitor, said preparation being adapted for (a) the administration of parathyroid hormone during a period of approximately 6 to 24 months; (b) after the administration of parathyroid hormone has been terminated, the administration of a bone resorption inhibitor during a period of approximately 12 to 36 months.

This application is a continuation of U.S. application Ser. No.12/351,558, filed on Jan. 9, 2009, which is a divisional of U.S.application Ser. No. 11/305,339, filed on Dec. 19, 2005, now U.S. Pat.No. 7,507,715, which was a continuation of U.S. application Ser. No.10/389,797, filed Mar. 18, 2003, now U.S. Pat. No. 7,018,982, which wasa divisional of U.S. application Ser. No. 09/942,661, filed Aug. 31,2001, now abandoned, which was a continuation of U.S. application Ser.No. 09/125,247, filed on Aug. 14, 1998, now U.S. Pat. No. 6,284,730,which was the National Stage of International Application No.PCT/SE98/01095, filed on Jun. 8, 1998, which claimed the benefit ofSwedish Application No. 9702401-2, filed Jun. 19, 1997 in Sweden. Thisapplication hereby incorporates by reference the U.S. and foreignpriority applications and patents enumerated herein.

TECHNICAL FIELD

The present invention relates to a combined pharmaceutical preparationcomprising parathyroid hormone and a bone resorption inhibitor, forsequential use in the treatment of bone-related diseases.

BACKGROUND

Bone Formation and Resorption

In the adult individual (males as well as females) bone is continuouslysubject to remodeling. This is a process where bone resorption isclosely linked to bone formation, through the concerted action of thebone active cells, i.e. the bone forming osteoblasts and the boneresorbing osteoclasts. These cells together form what is called a basalmulticellular (metabolic) unit, or BMU. The remodeling process startswith activation of the lining cells (the cells that cover theunmineralized bone). The lining cells resorb the unmineralized bone,then retract and leave room for the osteoclasts which resorb the old,mineralized bone and create an environment which attracts the osteoblastto the same site. The osteoblasts thereafter lay down the organicmatrix, which subsequently is becoming mineralized to form new bone. Theresulting bone mass is thus determined by the balance between resorptionby osteoclasts and formation by osteoblasts.

Consequently, there is a close relationship between the actions of thetwo cell types which is referred to as “coupling”; bone resorptionalways precedes bone formation. The coupling phenomenon means that evenwhen the intention is to produce a positive balance per cycle it isstill necessary to start with bone resorption. Typically, a BMU cycletakes 3 to 6 months to complete.

The rate by which the basal metabolic (multicellular) units are beingactivated, the activation frequency, also plays a role. A highactivation frequency increases the rate by which bone is being lost ifthere is a negative balance per remodeling cycle. When activationfrequency is increased the space that is being occupied by remodeling,the remodeling space, is also increased. This will give a lowered bonemass, since a greater portion of the bone is subject to resorption aspart of the remodeling process.

The above outlined sequence of events is well known in the art and hasformed the basis for the understanding of metabolic bone diseases andpossible ways for their treatments.

Osteoporosis is a disease which is characterized by a reduced amount ofbone tissue, usually of normal composition, which has reduced strengthdue to a combination of low bone mass and impaired architecture, andtherefore carries an increased risk of fractures. In terms ofremodeling, osteoporosis is the result of negative bone balance perremodeling cycle, i.e. less bone is formed than is being resorbed. In asmall proportion of patients it is possible to determine a specificdisease as responsible for the loss of bone (e.g. malabsorption ofcalcium and hypersecretion of corticosteroid hormones) but in themajority of patients no such disorder is identified. Such patients areclassified as having “primary” osteoporosis. Bone is lost with advancingage in both sexes, but in females there is generally an increased rateof loss during the first years after the menopause (hence the term“postmenopausal” osteoporosis).

Bone Resorption Inhibitors

A number of agents have been used for the prevention and treatment ofbone loss and osteoporosis, e.g. estrogen, vitamin D andbisphosphonates, such as alendronate (for a review, see: Osteoporosis(Marcus, R., Feldman, D. and Kelsey, F., Eds.) Academic Press, SanDiego, 1996). Such agents mainly act through inhibition of boneresorption. By reducing the resorbed amount in each remodeling cycle,while keeping the formation intact, it is possible to reduce thenegative bone balance and retard bone loss. At the same time they reducethe activation frequency and since the remodeling space is reduced thereis only a limited increase of bone mass.

Most studies with bisphosphonates indicate that they increase bonemineral density of the lumbar spine in the actively treated patientswith around 1 to 5%, depending on dose and type of bisphosphonate,during the first year of treatment, when compared with control patientsgiven placebo. Both patients and controls generally receive calciumsupplementation to ensure adequate calcium nutrition.

The antiresorptive agents can retard bone loss but, by definition, theydo not increase bone mass within each remodeling unit. Many patientswith fractures have severe bone loss at the time they come to clinicalattention. Inhibition of bone resorption might not be enough to preventfracture recurrences. Therefore it is urgent to develop therapies thatcan increase bone mass, i.e. anabolic agents.

Parathyroid Hormone

Parathyroid hormone (PTH) is an 84 amino acid polypeptide which isnormally secreted from the parathyroid glands. PTH has an importantphysiological role to maintain serum calcium within a narrow range.Furthermore, it has anabolic properties when given intermittently. Thishas been well documented in a number of animal and open clinicalstudies, recently reviewed by Dempster, D. W. et al. (Endocrine Reviews1993, vol. 14, 690-709). PTH has a multitude of effects on bone. Part ofit is through the remodeling cycle. PTH causes both increased activationfrequency and a positive balance per cycle.

Human PTH may be obtained through peptide synthesis or from geneticallyengineered yeast, bacterial or mammalian cell hosts. Synthetic human PTHis commercially available from Bachem Inc., Bubendorf, Switzerland.Production of recombinant human parathyroid hormone is disclosed in e.g.EP-B-0383751.

PTH when given alone, to a patient with osteoporosis, will stimulatebone formation within each remodeling cycle and cause a positive bonebalance within each cycle. At the same time the number of remodelingunits will greatly increase, i.e. the activation frequency is enhanced.These two mechanisms act in different directions on bone mass.

During therapy with PTH it has been calculated that the activationfrequency is doubled. Although this will mean that the remodeling spaceis increased, bone mass (or bone density) is increased in trabecularbone. Thus bone mineral density is increased by 5 to 10% per year in thelumbar spine and is largely unaffected in the femoral neck, whichcontains a higher proportion of cortical bone. These two sites are wherethe most common and clinically important fractures occur in thepopulation, both in males and females.

The presently known methods for treatment of osteoporosis utilize boneresorption inhibition of the BMU cycle, but have the drawbacks thattheir onset of effect is slow and limited, and that they only causemoderate increases of bone mineral density (bone mass) and may thereforebe insufficient for the treatment of patients with osteoporosis in astage where there is high risk of recurrent fractures. Furthermore, ithas not been shown that present methods can improve on the alteredarchitecture that is a hallmark of advanced osteoporosis.

A method of treatment of bone metabolism disorders, utilizing the orderof events in the BMU cycle, and comprising administering a bone activephosphonate and, sequentially, parathyroid hormone, is disclosed in WO96/07417 (The Procter & Gamble Company). In that method, the bone activephosphonate is given for a period of greater than about 6 months, invarious dosage regimens, but always prior to PTH.

Hodsman, A. et al. (J. Bone and Mineral Research, Vol. 10, Suppl. 1,abstract No. P288, p. S200, 1995) discloses a clinical trial involvingtreatment with PTH for 28 days, with our without sequential calcitoninfor 42 days, with this cycle repeated at 3 months intervals for 2 years.Patients were then crossed over to clodronate, 28 days per 3 months, forone year.

However, there was no beneficial effect in bone density from thissequential PTH/bisphosphonate treatment regimen.

WO 97/31640 (publication date Sep. 4, 1997) discloses a pharmaceuticalcomposition comprising (a) an estrogen agonist/antagonist; and (b) abone activating compound, such as parathyroid hormone. However, theperiods of treatment are broadly defined and it is stated that the saidcompounds can be administered for periods from about three months toabout three years.

DISCLOSURE OF THE INVENTION

Different combinations are conceivable for treating osteoporosis withresorption inhibitors and anabolic agents. The starting point fortreatment, i.e. when the patient comes to the attention of the clinic,is a decreasing BMD (bone mineral density), due to the net formationrate being below the net resorption rate. Initial administration of aresorption inhibitor will reduce resorption rate by reducing theremodeling space and the activation frequency. Subsequent administrationof an anabolic agent will then increase activation frequency and createan increased remodeling space. This coupling between resorption andreformation allows the formation rate to increase above the resorptionrate and lead to increases in BMD. The resorption activity is aprerequisite for subsequent bone formation within the BMU.

However, it has surprisingly been found that when the anabolic agent wasadministered initially, i.e. as the starting point, and is then followedby administration of the resorption inhibitor, the total increase in BMDis not only maintained but also much further increased. It appears thatthe initial increase in activation frequency by the anabolic agentcreates not only formation of new bone, but also a large remodelingspace. Subsequent administration by the resorption inhibitor, inhibitsfurther increases in the remodeling space, by decreasing the activationfrequency. Upon closing, or diminishing, the existing remodeling space,

BMD is then allowed to increase more than was achieved during treatmentwith the anabolic agent alone during the first period.

The present invention is thus based on the concept of remodeling. Byoverriding the resorptive phase of the BMU over several consecutivecycles, it fortifies the anabolic action of PTH. In addition, byprolonging the treatment over several BMU cycles, it takes advantage ofthe opposite influences on the activation frequency which is increasedby PTH and later reduced by bisphosphonates.

As mentioned above, WO 96/07417 discloses a method of treatment of bonemetabolism disorders, comprising administering a bone active phosphonateand, subsequently, parathyroid hormone. The bone active phosphonate wasthus given prior to PTH. The order of treatment regimens providesprincipally different treatment responses. Slowing down the remodelingcycle with a resorption inhibitor would limit the maximum anaboliceffect that can be obtained with PTH. On the other hand, if PTH is givenfirst over several BMU cycles, not only will it enhance the BMU positivebone balance significantly, it will also increase activation frequencyto such an extent that effects of subsequent antiresorptive therapy willbe enhanced.

According to the present invention, a bisphosphonate is given after PTHtreatment, in order not only to maintain bone mass on the higher levelby its antiresorptive action, but also to increase BMD by filling in theincreased remodeling space through the reduction of activationfrequency.

A BMU cycle, involving activation, resorption, formation, typicallytakes 3 to 6 months to complete. The number of BMU cycles actingconcurrently determines the remodeling space. In order to create anincreased and sustained remodeling space, treatment with an agent thatincreases the activation frequency must be of sufficient duration, i.e.it must cover several BMU cycles (e.g. 6 to 12 months). Only then canthe full potential of the treatment, with regards to increases in BMD,develop.

It has thus surprisingly been found that the method of treatmentaccording to the invention achieves the advantageous result that bonemass is first rapidly increased during PTH treatment and thereafterfurther bone mineral density is gained, compared to the results achievedwith bisphosphonates alone without prior activation by PTH. Thesefindings are in contrast to previous studies in humans.

Consequently, the present invention provides in a first aspect acombined pharmaceutical preparation comprising parathyroid hormone and abone resorption inhibitor, said preparation being adapted for (a) theadministration of parathyroid hormone during a period of approximately 6to 24 months, preferably about 12 (or above 12) months to 24 months orabout 12 (or above 12) months to 18 months, or more preferably about 18months; and (b) after the administration of said parathyroid hormone hasbeen terminated, the administration of a bone resorption inhibitorduring a period of approximately 6 to 36 months, preferably about 12 to36 months or about 12 to 18 months, or more preferably about 12 months.

This sequence of treatments can be repeated at intervals of one to fiveyears, until BMD has reached a value corresponding to “young normalmean”. Preferably, the interval between treatments coincides with theperiod of one treatment cycle, i.e. 12 to 60 months, preferably 24 to 60months or 24 to 42 months, or more preferably 30 to 36 months.

The term “parathyroid hormone” (PTH) encompasses naturally occurringhuman PTH, as well as synthetic or recombinant PTH (rPTH).

Further, the term “parathyroid hormone” encompasses full-lengthPTH(1-84) as well as PTH fragments. It will thus be understood thatfragments of PTH variants, in amounts giving equivalent biologicalactivity to PTH(1-84), can be incorporated in the formulations accordingto the invention, if desired. Fragments of PTH incorporate at least theamino acid residues of PTH necessary for a biological activity similarto that of intact PTH. Examples of such fragments are PTH(1-31),PTH(1-34), PTH(1-36), PTH(1-37), PTH(1-38), PTH(1-41), PTH(28-48) andPTH(25-39).

The term “parathyroid hormone” also encompasses variants and functionalanalogues of PTH. The present invention thus includes pharmaceuticalformulations comprising such PTH variants and functional analogues,carrying modifications like substitutions, deletions, insertions,inversions or cyclisations, but nevertheless having substantially thebiological activities of parathyroid hormone. Stability-enhancedvariants of PTH are known in the art from e.g. WO 92/11286 and WO93/20203. Variants of PTH can e.g. incorporate amino acid substitutionsthat improve PTH stability and half-life, such as the replacement ofmethionine residues at positions 8 and/or 18, and replacement ofasparagine at position 16. Cyclized PTH analogues are disclosed in e.g.WO 98/05683.

Consequently, the invention includes a preparation as described abovewherein the said parathyroid hormone is selected from the groupconsisting of:

-   -   (a) full-length parathyroid hormone;    -   (b) biologically active variants of full-length parathyroid        hormone;    -   (c) biologically active parathyroid hormone fragments; and    -   (d) biologically active variants of parathyroid hormone        fragments.

In this context, the term “biologically active” should be understood aseliciting a sufficient response in a bioassay for PTH activity, such asthe rat osteosarcoma cell-based assay for PTH-stimulated adenylatecyclase production (see Rodan et al. (1983) J. Clin. Invest. 72, 1511;and Rabbani et al. (1988) Endocrinol. 123, 2709).

The PTH to be used in the pharmaceutical preparation according to theinvention is preferably recombinant human PTH, such as full-lengthrecombinant human PTH. Parathyroid hormone can be subcutaneouslyadministered in an amount of approximately 0.1 to 5 μg/kg body weight,preferably 0.5 to 3 μg/kg, or more preferably 1 to 2.5 μg/kg bodyweight. Orally, nasally or pulmonary, PTH can be administered in anamount of 0.1 μg to 15 mg/kg.

The said bone resorption inhibitor can be a bisphosphonate, e.g.alendronate; or a substance with estrogen-like effect, e.g. estrogen; ora selective estrogen receptor modulator, e.g. raloxifene, tamoxifene,droloxifene, toremifene, idoxifene, or levormeloxifene; or acalcitonin-like substance, e.g. calcitonin; or a vitamin D analog; or acalcium salt.

The said bone resorption inhibitor is preferably administered in anamount of 0.05 to 500 mg, preferably around 10 mg.

In a further aspect, the invention provides the use of parathyroidhormone in combination with a bone resorption inhibitor in themanufacture of a medicament for the treatment or prevention ofbone-related diseases, in particular osteoporosis, said medicament beingadapted for (a) the administration of parathyroid hormone during aperiod of approximately 6 to 24 months; (b) after the administration ofparathyroid hormone has been terminated, the administration of a boneresorption inhibitor during a period of approximately 12 to 36 months.The parathyroid hormone and the bone resorption inhibitor are as definedabove.

In yet a further aspect, the invention provides a method of treatment orprevention of bone-related diseases, in particular osteoporosis, whichcomprises administering to a mammal, including man, in need of suchtreatment an effective amount of a pharmaceutical preparation as definedin the above. Consequently, such a method comprises administering to amammal, including man, in need of such treatment (a) an effective amountof parathyroid hormone during a period of approximately 6 to 24 months;and (b) after the administration of parathyroid hormone has beenterminated, an effective amount of a bone resorption inhibitor during aperiod of approximately 12 to 36 months.

The invention also includes a method of treatment or prevention ofbone-related diseases which comprises administering, to a patient whohas already been subject to treatment with parathyroid hormone during aperiod of approximately 6 to 24 months, after the administration ofparathyroid hormone has been terminated, an effective amount of a boneresorption inhibitor during a period of approximately 12 to 36 months.

EXAMPLE OF THE INVENTION

Postmenopausal females (n=172) with osteoporosis were given intact humanPTH(1-84), as a subcutaneous injection, for one year in doses from 50 to100 micrograms daily. It was shown that bone mineral density of thespine was increased in the lumbar spine, on the average by 8%. Increasesin individual patients were considerably more than 10%. The changes ofthe femoral neck were smaller and ranged from 1 to 3%.

When administration of PTH was interrupted, some patients (approximately60) were given the bisphosphonate alendronate in a standard dose of 10mg for one year. After the combined treatment, bone mineral density wasfurther increased in that group of patients. The average gain in thefemoral neck over the two years was 6% and of the lumbar spine 15%.Again, some individual responses were considerably larger and amountedto more than 25% in the spine.

These new observations demonstrate that it is possible to achieve anenhanced effect on bone mineral density with the sequentialadministration of PTH and bisphosphonates.

1. A combined pharmaceutical preparation comprising parathyroid hormone and a bone resorption inhibitor, said preparation being adapted for (a) the administration of parathyroid hormone during a period of approximately 6 to 24 months; and (b) after the administration of said parathyroid hormone has been terminated, the administration of a bone resorption inhibitor during a period of approximately 6 to 36 months.
 2. A combined pharmaceutical preparation according to claim 1, adapted for said administration of parathyroid hormone for approximately 12 to 24 months.
 3. A combined pharmaceutical preparation according to claim 2, adapted for said administration of parathyroid hormone for approximately 18 months.
 4. A combined pharmaceutical preparation according to claim 1 adapted for said administration of bone resorption inhibitor for approximately 12 to 36 months.
 5. A combined pharmaceutical preparation according to claim 4, adapted for said administration of bone resorption inhibitor for approximately 12 to 18 months.
 6. A combined pharmaceutical preparation according to claim 5, adapted for said administration of bone resorption inhibitor for approximately 12 months.
 7. A preparation according to claim 1 wherein the said parathyroid hormone is selected from the group consisting of: (a) full-length parathyroid hormone; (b) biologically active variants of full-length parathyroid hormone; (c) biologically active parathyroid hormone fragments; and (d) biologically active variants of parathyroid hormone fragments.
 8. A preparation according to claim 1 wherein the said bone resorption inhibitor is a bisphosphonate.
 9. A preparation according to claim 8 wherein the said bisphosphonate is alendronate.
 10. A preparation according to claim 1 wherein the said bone resorption inhibitor is a substance with estrogen-like effect.
 11. A preparation according to claim 10 wherein the said substance with estrogen-like effect is estrogen.
 12. A preparation according to claim 1 wherein the said bone resorption inhibitor is a selective estrogen receptor modulator.
 13. A preparation according to claim 12 wherein the said selective estrogen receptor modulator is selected from the group consisting of raloxifene, tamoxifene, droloxifene, toremifene, idoxifene, or levormeloxifene
 14. A preparation according to claim 1 wherein the said bone resorption inhibitor is a calcitonin-like substance.
 15. A preparation according to claim 14 wherein the said calictonin-like substance is calcitonin.
 16. A preparation according to claim 1 wherein the said bone resorption inhibitor is a vitamin D analog.
 17. A preparation according to claim 1 wherein the said bone resorption inhibitor is a calcium salt.
 18. Use of parathyroid hormone in combination with a bone resorption inhibitor in the manufacture of a medicament for the treatment or prevention of bone-related diseases, said medicament being adapted for (a) the administration of parathyroid hormone during a period of approximately 6 to 24 months; (b) after the administration of parathyroid hormone has been terminated, the administration of a bone resorption inhibitor during a period of approximately 12 to 36 months.
 19. The use according to claim 18, wherein said medicament is adapted for administration of parathyroid hormone for approximately 12 to 24 months.
 20. The use according to claim 19 wherein said medicament is adapted for administration of parathyroid hormone for approximately 18 months.
 21. The use according to claim 18, wherein said medicament is adapted for administration of bone resorption inhibitor for approximately 12 to 36 months.
 22. The use according to claim 21, adapted for said administration of bone resorption inhibitor for approximately 12 to 18 months.
 23. The use according to claim 22, adapted for said administration of bone resorption inhibitor for approximately 12 months.
 24. The use according to claim 18 wherein the said parathyroid hormone is selected from (a) full-length parathyroid hormone; (b) biologically active variants of full-length parathyroid hormone; (c) biologically active parathyroid hormone fragments; and (d) biologically active variants of parathyroid hormone fragments.
 25. The use according to claim 18 wherein the said bone resorption inhibitor is at least one of the group consisting of a bisphosphonate, a substance with estrogen-like effect, a selective estrogen receptor modulator, a calcitonin-like substance, a vitamin D analog, and a calcium salt.
 26. The use according to claim 18 in the manufacture of a medicament for the treatment of osteoporosis.
 27. A method of treatment or prevention of bone-related diseases which comprises administering to a mammal, including man, in need of such treatment an effective amount of a pharmaceutical preparation according to claim
 1. 28. A method of treatment or prevention of bone-related diseases which comprises administering to a mammal, including man, in need of such treatment (a) an effective amount of parathyroid hormone during a period of approximately 6 to 24 months; and (b) after the administration of parathyroid hormone has been terminated, an effective amount of a bone resorption inhibitor during a period of approximately 6 to 36 months.
 29. A method of treatment or prevention of bone-related diseases which comprises administering, to a patient who has already been subject to treatment with parathyroid hormone during a period of approximately 6 to 24 months, after the administration of parathyroid hormone has been terminated, an effective amount of a bone resorption inhibitor during a period of approximately 6 to 36 months.
 30. A method of treatment or prevention of bone-related diseases according to claim 27, adapted for said administration of parathyroid hormone for approximately 12 to 24 months.
 31. A method of treatment or prevention of bone-related diseases according to claim 30, adapted for said administration of parathyroid hormone for approximately 18 months.
 32. A method of treatment or prevention of bone-related diseases according to claim 27, adapted for said administration of bone resorption inhibitor for approximately 12 to 36 months.
 33. A method of treatment or prevention of bone-related diseases according to claim 32, adapted for said administration of bone resorption inhibitor for approximately 12 to 18 months.
 34. A method of treatment or prevention of bone-related diseases according to claim 33, adapted for said administration of bone resorption inhibitor for approximately 12 months.
 35. The method according to claim 27 wherein the said parathyroid hormone is selected from (a) full-length parathyroid hormone; (b) biologically active variants of full-length parathyroid hormone; (c) biologically active parathyroid hormone fragments; and (d) biologically active variants of parathyroid hormone fragments.
 36. The method according to claim 27 wherein the said bone resorption inhibitor is at least one of the group consisting of a bisphosphonate, a substance with estrogen-like effect, a selective estrogen receptor modulator, a calcitonin-like substance, a vitamin D analog, and a calcium salt.
 37. The method according to claim 27 for the treatment of osteoporosis. 